在Python多处理库中,是否有支持多个参数的pool.map变体?

import multiprocessing

text = "test"

def harvester(text, case):
    X = case[0]
    text + str(X)

if __name__ == '__main__':
    pool = multiprocessing.Pool(processes=6)
    case = RAW_DATASET
    pool.map(harvester(text, case), case, 1)
    pool.close()
    pool.join()

当前回答

import time
from multiprocessing import Pool


def f1(args):
    vfirst, vsecond, vthird = args[0] , args[1] , args[2]
    print(f'First Param: {vfirst}, Second value: {vsecond} and finally third value is: {vthird}')
    pass


if __name__ == '__main__':
    p = Pool()
    result = p.map(f1, [['Dog','Cat','Mouse']])
    p.close()
    p.join()
    print(result)

其他回答

text = "test"

def unpack(args):
    return args[0](*args[1:])

def harvester(text, case):
    X = case[0]
    text+ str(X)

if __name__ == '__main__':
    pool = multiprocessing.Pool(processes=6)
    case = RAW_DATASET
    # args is a list of tuples 
    # with the function to execute as the first item in each tuple
    args = [(harvester, text, c) for c in case]
    # doing it this way, we can pass any function
    # and we don't need to define a wrapper for each different function
    # if we need to use more than one
    pool.map(unpack, args)
    pool.close()
    pool.join()

从Python 3.4.4中,您可以使用multiprocessing.get_context()获取上下文对象,以使用多个启动方法:

import multiprocessing as mp

def foo(q, h, w):
    q.put(h + ' ' + w)
    print(h + ' ' + w)

if __name__ == '__main__':
    ctx = mp.get_context('spawn')
    q = ctx.Queue()
    p = ctx.Process(target=foo, args=(q,'hello', 'world'))
    p.start()
    print(q.get())
    p.join()

或者你只是简单地替换

pool.map(harvester(text, case), case, 1)

具有:

pool.apply_async(harvester(text, case), case, 1)

另一种方法是将列表列表传递给单参数例程:

import os
from multiprocessing import Pool

def task(args):
    print "PID =", os.getpid(), ", arg1 =", args[0], ", arg2 =", args[1]

pool = Pool()

pool.map(task, [
        [1,2],
        [3,4],
        [5,6],
        [7,8]
    ])

然后可以用自己喜欢的方法构造一个参数列表。

这里有很多答案,但似乎没有一个能提供适用于任何版本的Python 2/3兼容代码。如果您希望代码能够正常工作,这将适用于以下任一Python版本:

# For python 2/3 compatibility, define pool context manager
# to support the 'with' statement in Python 2
if sys.version_info[0] == 2:
    from contextlib import contextmanager
    @contextmanager
    def multiprocessing_context(*args, **kwargs):
        pool = multiprocessing.Pool(*args, **kwargs)
        yield pool
        pool.terminate()
else:
    multiprocessing_context = multiprocessing.Pool

之后,您可以使用常规的Python3方式进行多处理。例如:

def _function_to_run_for_each(x):
       return x.lower()
with multiprocessing_context(processes=3) as pool:
    results = pool.map(_function_to_run_for_each, ['Bob', 'Sue', 'Tim'])    print(results)

将在Python 2或Python 3中工作。

import time
from multiprocessing import Pool


def f1(args):
    vfirst, vsecond, vthird = args[0] , args[1] , args[2]
    print(f'First Param: {vfirst}, Second value: {vsecond} and finally third value is: {vthird}')
    pass


if __name__ == '__main__':
    p = Pool()
    result = p.map(f1, [['Dog','Cat','Mouse']])
    p.close()
    p.join()
    print(result)